Glucose-6-phosphate dehydrogenase (G6PD) deficiency, a hereditary X-linked disorder, is the most common enzymatic disorder of red blood cells in humans, affecting more than 200 million people worldwide. The prevalence is increasing in the Netherlands due to immigration of people from the Middle East and Africa. We present three different clinical manifestations of G6PD deficiency: neonatal jaundice, haemolysis provoked by infection and haemolysis caused by fava beans. The pathophysiology and treatment are discussed. Furthermore a recent update of chemicals which should be avoided in G6PD deficiency is provided.